return usbdux_pwm_pattern(dev, s, CR_CHAN(insn->chanspec), data[0], 0);
 }
 
-static int usbdux_pwm_read(struct comedi_device *x1,
-                          struct comedi_subdevice *x2, struct comedi_insn *x3,
-                          unsigned int *x4)
-{
-       /* not needed */
-       return -EINVAL;
-};
-
 static int usbduxsigma_pwm_config(struct comedi_device *dev,
                                  struct comedi_subdevice *s,
                                  struct comedi_insn *insn,
                s->n_chan       = 8;
                s->maxdata      = devpriv->sizePwmBuf;
                s->insn_write   = usbdux_pwm_write;
-               s->insn_read    = usbdux_pwm_read;
                s->insn_config  = usbduxsigma_pwm_config;
 
                usbdux_pwm_period(dev, s, PWM_DEFAULT_PERIOD);